🤰 Pregnancy Calculator
Estimate your due date, current gestational age, and trimester based on your last menstrual period or conception date.
Your Details
Your Result
This calculator provides estimates only. Only around 5% of babies are born on their exact due date. Consult your healthcare provider for accurate dating, especially via ultrasound.
How the Pregnancy Calculator Works
Pregnancy is typically dated using Naegele's rule, which adds 280 days (40 weeks) to the first day of your last menstrual period. If you know your conception date instead, 266 days (38 weeks) is added to that date.
Formula
Due date (from conception) = Conception date + 266 days
Gestational age (weeks) = (Today − LMP) / 7
Trimesters
- First trimester: Weeks 1–13
- Second trimester: Weeks 14–27
- Third trimester: Weeks 28–40
Frequently Asked Questions
How is my due date calculated?
Most due dates are estimated by adding 280 days to the first day of your last menstrual period, adjusted for your average cycle length.
How accurate are pregnancy due dates?
Due dates are estimates. Only about 5% of babies are born on their exact due date; most arrive within two weeks before or after.
When does gestational age start counting?
Gestational age is counted from the first day of your last menstrual period, even though conception typically occurs about two weeks later.